It's not at all a dumb question. At some point, a radio became standard equipment.
'Radio delete' is a misnomer. A radio, even the cheapest AM, was an extra-cost option at least into the '70s. If no radio was ordered, the area on the dash panel where it mounted was covered with a metal or plastic cover ['block-off plate']. In addition, the front speaker grille in the dash structure was covered with cardboard; the hole in the hinge pillar for the antenna was plugged. In the case of a few cars [1968 & 1970s Novas] the plastic dash panel had no provision for a radio. In the engine bay, there were no radio ground straps.
Dealers often did it on stock orders because the Motorola knock-off radio was half the cost on the factory unit. However, more than a few Chevrolet Dealers found that ordering significant numbers of cars without a factory-installed Delco radio earned them a visit from a Zone Rep. The Rep would remind them Delco was a GM division and it they persisted, order delays might result.
